NA Koni Sports vs. '99 Bilstein Sports - Shock Dynos - Miata Turbo Forum - Boost cars, acquire cats.

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Old 02-23-2010, 07:01 PM   #1
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Default NA Koni Sports vs. '99 Bilstein Sports - Shock Dynos

If someone gave you this chart and told you this is how these shocks compare on the dyno, what would this really give away?



I'm thinking about moving from my konis to the bilstiens on my 550/300 combo or 400/250. Currently the Konis are harsh and jack down on the heavier rates, with FM springs they would okay, but still always felt "stiff" when driving, I believe it's due to the high rebound and jacking down effect. So I picked up the 400/250 rate springs to be in the middle of my FM springs prior. It seems to be written these bilstiens can handle 450/300 rates without valving and ride smoother and work better than konis, but I'm trying to see how each of these compare since it seems they have opposite characteristics in relation to compression and rebound. Any expert advice?
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Old 02-23-2010, 07:13 PM   #2
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comparison!



not sure if the sign convention is the same.
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Old 02-23-2010, 08:44 PM   #3
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Also, any reason some charts label compression and rebound reverse from others?

Like the chart you posted is in reverse. I used one provided from koni, I know the rebound is on the top because the konis only adjust rebound.

I took the Bilstiens from here:






the konis:http://forum.miata.net/vb/attachment...chmentid=10097
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Old 02-24-2010, 09:47 AM   #4
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I know how to read those, but still don't know what's good and what's bad.
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Old 02-24-2010, 10:06 AM   #5
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Exactly. It seems the Konis have far superior rebound at low and high speeds when adjusted full stiff. And they also match the Bilstiens at low-speed bump (bilsteins have a slight advantage at 2-3 in/sec) but have far more mid/high bump. Beyond that... I'm not sure what I'm looking for out of a shock.

Here's what I dont like about my konis: With 550/330 springs (I know a little much for the valving, so I read) they handle great when I'm out fooling around or when I've autoxed on the setup far better than the FM springs. Driving on the highway is smooth and precise. However, I have to avoid potholes or any other impurities like a devote Christian. I tend to brace myself before I'm about to hit something. It's harsh, and I believe due to the high rebound I don't glide over holes the wheel is forced down into them. This probably makes them a great autoxing shock on smooth pavement to get ultimate grip.

I can almost handle the harshness, but for how the rear reacts. On FM springs it always felt smooth, a bit stiff driving, but not like a blown stock suspension. When I hit dips in the road the rear end feels like it's going to skip and I have the launching effect in my butt where I feel like I'm going to get thrown out of the car. I don't like this. I notice it the most when going over speed bumps, I drive over them fine, but when the rears start to roll down off them, I feel like they catapult me upwards. I don't like this.

I just recently purchased new NB tophats for the Front, ISC Racing Tophats for the Rear, and 400/250 springs. I figured these springs would but me in the middle of the 318/233 FM combo and the 550/300 current combo and be more within the Koni's valving.

I have the opportunity to purchase a set of '99 bilstiens and would most likely get them valved. I'm not sure it's worth the investment or if it'll benefit from them. I hear people ranting and raving about the FCM bilstein valving and how comfortable the ride can be with heavier spring rates. This is what I ultimately want, but do not understand why exactly the bilstein can do this when I look at the dynos and don't really see what gives it away.

Once I swap the new spring in I'll probably be done with it, I've driven a few CG/Koni setups (375/250) and it felt like it drove well enough. I've taken a few steps recently into downgrading some performance parts to make the car a more comfortable street DD vehicle, but I still want it to perform very well when I do get out to the track or autox. And since I'm a big jew face it's hard for me to justify spending money on old shocks when I have 4 that still work
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Old 02-24-2010, 11:03 AM   #6
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pay attention to the steepness of the line

the velocity of the shaft--knowing that below ~3-5 in/sec is handling and response and above 5-6 ips is ride comfort and traction.

this is why most shocks are steep on the left and shallower on the right. having a linear shock means you have SUPER stiff ride over bumps OR soft handling like a caddy.

moving that "elbow" to the right increases the performance threshold while sacrificing ride comfort and potentially traction over rough surfaces.

rebound tends to mostly address spring rate.

bump tends to mostly address responsiveness and ride quality.
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Old 02-24-2010, 05:03 PM   #7
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Quote:
Originally Posted by Braineack View Post
I've taken a few steps recently into downgrading some performance parts to make the car a more comfortable street DD vehicle, but I still want it to perform very well when I do get out to the track or autox. And since I'm a big jew face it's hard for me to justify spending money on old shocks when I have 4 that still work
^^^This

What setup will provide comrotable DD, but allow you to remain competitive at a DE if you were up against a well sorted miata?

DO we hav any vendors that could get us a group buy on the bilsteins? The we could try to talk stewart development into a slight group revalve discount. I too, speak jew!
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Old 02-24-2010, 05:17 PM   #8
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Quote:
Originally Posted by djp0623 View Post
^^^This

What setup will provide comrotable DD, but allow you to remain competitive at a DE if you were up against a well sorted miata?

DO we hav any vendors that could get us a group buy on the bilsteins? The we could try to talk stewart development into a slight group revalve discount. I too, speak jew!
I'm in for a group revalve.
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Old 02-24-2010, 05:23 PM   #9
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Originally Posted by lsc224 View Post
I'm in for a group revalve.
stewart development also cells the bilstein shocks for $115.

Maybe we could talk him into a revalved shock group buy for $600 if we got enough people. How can we drum up interest?

I will quit thread jacking now
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Old 02-24-2010, 05:33 PM   #10
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IMHO, konis are a better choice for a dual purpose track/DD car. You can soften them for the street and stiffen them for the track. Plus you get the ability to tune your car for different conditions. The bilsteins are great shocks and I love the fact that they are monotube vs. twin tube, but not being adjustable kills it for me. The ideal shock is a monotube adjustable in both bump and rebound, but most on here will never pony up for a shock of that caliber. I have them on my E-Stock car and it made all the difference in the world on the track, but they can be turned down to ride very comfortably on the street. You get what you pay for and at almost 4K for a full set they should give you a BJ while you are driving too.
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Old 02-24-2010, 11:22 PM   #11
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Originally Posted by sbrian2 View Post
You can soften them for the street and stiffen them for the track.
I think you kinda lose that when the springs are stiffer than stock myself. My KYBs only have one setting front/rear that don't completely suck.
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Old 02-25-2010, 12:03 AM   #12
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Good reading here if you have not seen it...

DGs Autocross Secrets aka Autocross to Win - Shocks

Just a warning that Tein owners will not want to read.....

I have Tokico's and think they are probably crap.
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Old 02-25-2010, 12:59 AM   #13
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I read that. still give little to nothing away. doesn't even explain how to read a dyno, but just states over and over they are important. The only good info is his 65% critical dampening number.
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Old 02-25-2010, 01:34 AM   #14
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Nice link. I really like his prescription for tuning your shocks. My Konis were dynoed before installation by a buddy with access to a shock dyno, and they don't match. I run an offset L/R in the adjusters, and it seems to get me reasonably close, by seat of the pants. The DA Konis I had on my BMW also didn't match perfectly L/R, but the car worked friggin' great.

I also strongly agree with his position that once the shocks are tuned, they are tuned. Hard on the track and soft on the street is kinda like camping sober - it just doesn't make any sense.

Brain, some of what you said makes me question it, but I would seriously investigate to what extent you are bottoming out the rear suspension over bigger bumps. Getting my car up off the rear bumpstops made a huge improvement in ride and handling.

Last edited by SolarYellow510; 02-25-2010 at 02:00 AM.
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Old 02-25-2010, 01:45 AM   #15
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good thing I bought ISC racing tops hats huh?

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Old 02-25-2010, 01:51 AM   #16
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Quote:
Originally Posted by Braineack View Post
good thing I bought ISC racing tops hats huh?
I'll be doing the same thing with mine after they are revalved. Those should really help out. (They look to be painted better than they used to be lol)
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Old 02-25-2010, 01:59 AM   #17
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doesn't mean they are welded better...


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Old 02-25-2010, 02:05 AM   #18
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I do agree with the impact harshness you note. Not sure what the differences are between NA and NB Koni Yellows, but my Miata passes the impacts through a lot more than the BMW did with much higher spring rates. The DAs were adjusted with very little bump rate.

Unsprung weight also makes a huge difference. The 17x8s on my BMW were within 2 lb. of the 15x7.5 Rotas on the Miata, and I always believed that was a huge part of why the car worked so well. Recently picked up a set of 15x7 SSRs locally. Can't wait to get them on.
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Old 02-25-2010, 05:01 AM   #19
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I can get the Bilstein sport shocks for 90 each front and rear. If we get a lot of people i could talk my wholesaler down easy.
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Old 02-25-2010, 05:07 AM   #20
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I'm looking at bilstein's as well. I've heard nothing but good things about them. The only thing i have to compare bilsteins to would be a friends set of ohlins on his NA, and my stock suspension with 170k miles on it.

Now I'm looking to order a set of Fat Cat Motorsport bilsteins but as always, open to alternatives. Looking at 450/325, which is roughly the same springrate the ohlins run, I just hope they drive as well or better. I understand the advantage of having a non-ajustable coilover, one tuned and dynoed so they all match, but it feels a bit like gambling, i'm glad FCM offers a 60 day return policy.. I just want the car to be more fun and for me, super stiff is not that.

GL with your hunt Braineack, I'll be watching this thread closely, a bilstein sport group buy deal would be sick.
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